This invention relates to tracking radars, and in particular to means for eliminating degrading effects due to pulse to pulse variations of amplitude of received signals in sequentially lobed and conical scan tracking systems.
Tracking radar systems measure the coordinates of a target and provide data which may be used to determine the target path and predict its future position. The antenna beam in the tracking radar is positioned in angle by a servomechanism actuated by an error signal. The various methods for generating the error signal are classified as sequential lobing, conical scan, and simultaneous lobing or monopulse. Sequentially lobed and conical scan systems must process multiple received pulses (at least four) in order to determine target positions. The accuracy of this type of system is severely degraded if the amplitude of any received pulse is varied due to any factor other than lobing. Monopulse systems determine target position from a single returned signal pulse and are thus not subject to this source of error. Monopulse systems are, however, much more complex and have rigid channel matching requirements. Monopulse systems have been developed that eliminate channel matching through the use of single signal channel processing. This technique unfortunately introduces further problems associated with injecting lengthy delays (in terms of wavelengths) in the receiver to permit ordinary time sharing of a single signal channel.
The present invention is directed toward achieving single pulse derivation of tracking error signals without the normal complexity and channel matching requirements of a full monopulse system and without the time sharing problems of single signal channel processing.